Pump and stroke adjusting mechanism



Jan- 11, 1949- `HJ.AND1-:vesoul ET A1.'` 2,458,821

PUMP AND STROKE ADJUSTING MECHANISM4 Filed Feb.' 5, 1945 :s sheets-sheet1 Jam.A 11, 1949.

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PUMP AND STROKE ADJUSTING VMECHANISM Filed Feb. 5, 1945 A 3 Sheets-Sheet5 Patented Jan. 11, 1949 PUMP AND STROKE ADJUSTING MECHANISM Harry J.Anderson and Milton V. Hartman, Chicago, Ill., assignors toHills-McCanna Company, Chicago, Ill., a corporation of IllinoisAppiication February 5, 1945, Serial No. 576,180

1s claims.

This invention relates to piston or displacement type pumps and to meansfor adjusting the stroke thereof.

An object of the invention is to provide a novel means for adjusting thestroke of piston or displacement type pumps.

Another object of the invention is to provide a piston or displacementtype pump equipped with a hydraulic stroke adjustment means.

Still another object of the invention is to provide a novel pump capableof pumping two different liquids simultaneously in varying proportions.

Other objects of the invention will become apparent from the followingdescription and drawings of which:

Figure l is a plan view with afragment in cross-section of the novelstroke adjusting device and pump;

Figure 2 is a vertical cross-section of the novel stroke adjustingdevice and pump taken on the line II of Figure 1;

Figure 3 is an enlarged plan view with a fragment in cross-section ofthe driving mechanism for the stroke adjusting device and pump;

Figure 4 is an enlarged vertical cross-section taken on the line 4-4 ofFigure 2, showing the details of the inlet and outlet valves of thestroke adjusting device; and

Figure 5 is an enlarged horizontal cross-section through the `center ofa clutch shown in Figure 1.

Figure 6 is an enlarged isometricv view of a roller and guide blocksforming part of the device.

VReferring to the drawings, the numeral I represents a casing in whichall moving parts of the stroke adjusting device are enclosed with theexception of a portion of the crankshaft 3 which projects beyond theside of the casingk in order that it may be connected to a suitablesource of power capable of imparting thereto rotary motion at thedesired speed. The casing is provided with flanges 5 extendinghorizontally from the bottom of the casing, provided with holes 1 sothat the casing may be bolted firmly to a suitable foundation. Thecasing is also provided with a drain plug 8 at the bottom of the sidewall.

The crankshaft is rotatably supported by roller bearings 9 (Fig. 1) heldin place between two sets of inner bearing races I I and outer bearingraces I3. Inner cylindrical spacer I-5 and outer cylin-y drical spacerl1 are provided between the ltwo sets of inner and outer bearing races.The roller bearings and races are enclosed in a cylindrical housing I9which is rigidly bolted to the side of the casing I by means of threadedbolts 2l,

which pass through suitable holes 23 in the ange 25 of the housing I9and screw into threaded recesses tapped in the side of the casing inalignment with the holes 23. An end plate 21 having a circular openingin the center thereof to accommodate the shaft 3 is bolted to thehousing I9 by means of threaded bolts 29 passing through holes 3| in theplate and adapted to be screwed into threaded recesses tapped in thehousing in alignment with the holes 3|. A ring seal 33 adapted to fit ina recess in the end plate 21 provides a seal between the shaft 3 and theend plate to prevent leakage of oil.

The inner end of crankshaft 3 is rigidly fastened to crank 35. As isshown in Figures 1 and 3, a crankarm 31 is fastened to crank 35eccentrically with respect to crankshaft 3. The crankshaft, crank andcrankarm are preferably cast and/or machined as a single unit. Thecrankarm extends horizontally from the side of the crank opposite thatto which the crankshaft is fastened. 'I'he crankarm 31 is adapted torotate on roller bearings 39 held in place by inner bearing race 4I andouter bearing race 43. The races 4I and 43 are held in place betweenwashers 45 by meansof a snap ring 41 which fits in an annular groove onthe free end of the crankarm 31.

The outer bearing race 43 is confined between two spaced verticalrectangular plates 49 and 5I having hardened, machined surfaces. Eachplate is fastened to the inside of a split cross-head 53l comprising thetwo halves 55 and l51 bolted together by means of four bolts 59 threadedat their ends to receive nuts 6I. Each plate 49 and 5I is fastened toits respective half of the cross-head by means of screws B3 andcountersunk screws 64 adapted to pass through holes 65 in the plates 49and 5I along the edges thereof and to screw into threaded recesses 61tapped into each half of the cross-head. The plates 49 and 5I aredrilled and the cross-head halves are tapped identically along bothedges in order to permit them to be turned periodically and therebyequalize wear thereon. The crankarm 31 with the roller bearings 39 andbearing races 4I and 43 is adapted to reciprocate in a verticaldirection between the plates 49 and 5I Each half 5-5 and 51 of thecross-head 53 is formed integrally with a horizontally extendingcylinder 69 adapted to reciprocate in a bearing 1I held tightly in placein bore 13 in the end of the casing l. Passageways 15 are provided -topermit breathing and ingress and egress of oil to and from the space 16.

The stroke adjusting device and pump may be formed with two identicaicounterparts, one on each side of the median line C-C for feeding adifferent liquid from each side. The unit shown in the drawingsJ isdesigned for single feed and hence only. the portion of the unit on theright side of they median line has been equipped with the necessaryvalves, plungers, adjusting mechanism, etC.

liquid the left half of the apparatus will` ber` a mirror image of theright half.

Referring now particularly to. Figures 2 and.4,. the cylinder 68,adjacent the. juncture witlrthev right half 51 of the crosseheadhasrtvvo'ldia.-u

metrically Opposite threaded bores and 11 tapped therethrough toaccommodateA inlet and outlet valves, indicated generally by thenumerals 13 and 8|, respectively. The inlet or suction valve comprisesthe seat 83Y having a threaded stem 85 adaptedtobei screwed' into thebore 1'5 and'having an'axalpassageway 81", aV body 89 adapted to bescrewedionto the outer end of the seat, 83 and lockediirrplace by nut98, anda steel ball `9| The steerball is. preventedfrom rising'too high`and closing off passageway. 81 by means of* the pin 92I` extendingacrossA the passageway a short distance'ab'ove the ball. The'body lhasan axial bore=93"t^erminati`ng short of ltheouter end'thereof` and athreaded" horizontal bore ii'from the out.- side to the bore 93'. An oilfilter 91' is adapted to be-screwedint'o'thebore;95. The ball 9| closesthe passageway through theu valve on the discharge'lstroke of the pump.

TheoutletA or discharge valve 8| comprises theseat99-having"the`threaded stem |81 adapted to bescrewed into the' boreHandhaving an axial passageway4 |03', a` body |05adapted to, be screwedonto theouter'end of the seat 99'and locked in place by nut |01,steelballs |89 andvv separated' thanthestem portion ofthe Tsliapedpassagel wayy lil-51 The bore |1l accommodates aY plunger I9 having' a=smaller bottom' portion |28v which engages the .ball |Ii|. A roller |2|`is rotatably mounted in theplunger H8 adjacent the top thereof" withthev top of the roller extending beyond the *top ofthe plunger.

'The cylinder'lll is also provided; adjacent the juncture thereof `withthe right half 5'1 of the cross-head, with' arelief` valve |22',composed of a body |23'y having a small T-sliaped passageway |24;l avklarger axialfbore |25L threaded at its outer endt'o'reeeive adjustablescrew plug |26 held in position by1cotter pin |21', steel ball |28 andhelical spring'l29" adapted'to-holdthe ball |28 on itsseat.

Asealfp1i1g|30 having a recess to accommodate sea'lring' |3f|flts snuglyin the end ofthe cylinder 69 adjacent drive plate 5|. The centralythickened portion |32" of the plug |3'is press-fitted intovthe-recess|33t inthe drive plate 5|.

R-effrringnow t'o Figures' 1 and 2, a bracket |34* is boltedby meansofboltsv |35y to the side ofthe casing opposite theside-from which thecranksliaft 3 projects, at` a point adjacentA the top thereof andexactly alongl the median line CL-C.`

It is to be understood, however, thaty where both ends of the unit areused to feed" The bracket |34 is provided with two, vertically spacedhorizontal bores |38 and |31 Ialong lines directly above roller |2|. Ahorizontal, cylindrical stern |38, having a portion thereof threaded asshown at |39 is rotatably supported at one end by the bore. |36inbracket |34 and passes through a borein the end wall of the casing.The end of the stern |38 projecting outside the casing is provided witha handwheel |48. An elongated cam |4|, threaded at one end to engage thethreads |39 of thestem` |38;.is mounted on the stem and adapted tovtravel back and forth thereon upon turning the stem. A guide rod |42` ismounted directly above the threaded portion |39 of the stem. One end ofthe rody |42 is supported in the bore |31 in bracket |34 and held fastby set screw |43. The other endl ofthe rod |42 rests in a slot |44 onthe top side of the cam 4| and prevents the cam from rotating with therotation of the stem.

The bottom, left end |45. of the cam I4| is bevelled tofengage roller|2| and depress it.

A gear' |4i1` is rigidly mounted` on the stem |38v by means of set screw|49 against the inside wall ofthe casing, As is; apparent from. thedrawing stem |38'cann'ot move in a horizontal direction.

As shown in Figures 1 and`5 a reversible electric motor |51 is fastenedby means of screwsv |53 to thesameside' wall of the casing and at thesame level asbracket |34'. The motor |5| is adapted to. drive a gear |55through a clutch mechanism indicated generallyby the numeral |51. Thecl'ut'ch comprises a plate |59y rigidly mounted on the motor shaft |6|by means of a set screw |63, a driven plate (i5- formed with a stem |61upon which gear |55" is rigidly mounted by means of set screw |69, ahelical spring |1| mounted in a recess in stem lli-1, a steel ball |13,a spring retaner' |15f between ball |13V and spring |1|, and a drum |11threaded to screw onto plate |59 and having a' central boreto'accommodate stem |61. The' drum |11 is rigidly mounted on plate|59'by means 0f set screw |19. The spring |1| holds the" adjacent facesof p late and drum |11 in Contact with each other. Gear |55 meshes withgear |41 The end ofthe stem |61 is supported ina recess in'thelend'wallof the casing.

It will beunderstood-tliat the motor and clutch may be omitted and theAcam |4| adjusted .by turning handwheel |40 instead of by operationoffmotor |511 Still' referring to-Figures land 2, the numeral |83indicates af sump adapted to be filled with oil` and having a drain plug|84 at the bottom thereof. The sump |83 is fastened to the end loft caseby means of studs |85 and nuts |81.

A' ring'sealv |89 is provided between the casing and'sump to preventleakage. The wall ISI of the sump-is provided with a horizontal boreco-axial with cylindery 69. A plunger |93 extends from cylinder' 69through the bore in wall |9| into sump' |835 The plunger |93 is mountedto reciprocate-in a bushing |95 rigidly mounted in the endof" cylinder69; The end |81 of the plunger isformed with an enlarged head of smallerdiameter than cylinder 69 but adapted to abut against the ihner'end ofbushing |95 at full stroke andf on the suction stroke of the pumpingunit. Suitable ring seals |98 are placed in recesses in the bushingv |95and wall |9| to prevent leakage. An annularrecess |99; connected to apassageway 2882 is provided in the sump wall between ring seals` |983'to permit oil to escape therefrom and thereby indicateif theseals areleaking.

Instead of formingl cylinder 69' with a narrow end providedwitli abushing in which a plunger having an enlarged head is adapted toreciprocate, the cylinder 69 may be of uniform inside diameter and apiston may be snugly mounted in the cylinder to reciprocate. The pistonwill be connected to coupling 200"V by means of a connecting rod in thesame manner as the plunger |93 shown in the drawing.

The end of plunger |93 extending into sump |83 is threaded as shown at200 to receive a coupling 200". The coupling is rigidly fastened to theend of plunger |93 by means of set screw 200'". Coupling 200" isT-slotted as shown at 20| to receive coupling 203. Coupling 203 isprovided with a threaded stem 205 on which is adapted to be screwed pumpplunger or piston 201. Piston 201 is rigidly fastened to stem 205 bymeans of set screw 209. A pump body or cylinder 2| 0 is fastened to theend wall of sump |83 by means of studs 2I| mounted in the end wall 2|2of sump |83, and nuts 2|3. The pump body is provided with a flange 2I54having a plurality of spaced holes in alignment with studs 2| I. Asuitable ring seal 2 I1 is provided between the end wall 2 I2 and flange2 I5 to prevent leakage. A throat bushing 2 I9 is rigidly mounted' inthe pump body 2|0 in order to provide sliding surfaces for piston 201. Agland 22| is mounted at the end of the pump cylinder adjacent the sump.Gland 22| is held tightly in place by m-eans of studs 223, mounted inthe end wall 2I2 of the sump, and nuts 225. The gland is provided withholes in alignment with studs 223 through which the studs can pass.Gland 22| provides sliding support for the piston 201. Suitable packing221 is provided between the piston and pump cylinder to prevent leakage.A lantern ring 229 is provided between the piston 201 and pump body 2|0to which lubricant is furnished by means of a screw, plunger-typelubricator 23|.

The outer end of the pump body is closed" by means of screw plug 233 andthe body is provided adjacent its outer end with a threaded inlet 235and a threaded outlet 231.

An angle 239 is bolted to the bottom of end wall 2|2 of the sump bymeans of Vbolts 24|. The angle 239 is provided with holes 243 toaccommodate bolts 24| and with holes 245 to enablel the angle to befastened to a foundation.

The bore 13 at the left end of casing I as r shown in Figure 2, iscovered with lan end plate 241 held in place by studs and nuts, in thesame manner as sump |83 on the opposite end of the casing. A ring seal249 between the casing and end plate prevents leakage. It will beunderstood that when the left side of the unit is to be used to pumpliquid the end plate is removed and replaced with a sump identical withsump |83. Bore 25| through which the adjusting stem will pass when theleft side of the unitv is used, is plugged with a suitable expansionplug 253 when not in use.

Referring to Figures 2 and 6, mounted on they A guide roller 259 ismounted on a 1at-y against the surface of either bar as the crossheadreciprocates. The guide-bars and roller serve to keep the cross-head andcylinders 59 from turning.

Although the unit is shown as being open at the top, it may be suppliedwith suitable covers adapted to be screw fastened to the top of thecasing and sump.

Theunit operates as follows: In the position shown in Figure 2 the pumpis at the end of its discharge stroke with the stroke adjustmentmechanism set for full stroke. Upon further revolution of crankarm 31the cross-head 53 will bev forced to move to the left pulling with itplunger |93 and piston 291. The cylinder 59 is full of oil or otherhydraulic fluid sucked in from the casing through valve 19. Since iiuidcannot escape from cylinder 59 through either valve 19 or 8| as long ascam Mil is in the position shown, lthe unit will continue to operate atfull stroke unless pressure on the outlet of the pump during'dischargeexceeds the pressure for which relief valve |22 is set. If this occursfluid will escape from cylinder 69 through relief valve |22 as thecylinder completes its forward stroke but the forward motion of plunger|93 will stop. Upon the return stroke of the cross-head and cylinder 69,plunger E93 will remain stationary until the enlarged head |91 abutsagainst the end of bushing |55. The backward movement of cylinder 69while plunger |93 remains stationary creates suction in cylinder 59,drawing oil into the cylinder from the casing through valve 19 until thecylinder is again filled with oil and is ready for its next forwardstroke. Thus, if pressure in the delivery lines exceeds the pressure forwhich the relief Valve is set, plunger |93 will remain stationary whilecrosshead 5I and cylinder 59 continue to recipro cate through their fullstroke.

Now assume that cam MI is shifted to the left either by means of themotor 55| or by manually turning handwheel |40. When the roller I2!abuts against the cam, the roller is depressed,r in turn depressingplunger H9 and ball |||.l The loading on spring lili is not sufficientto keep ball E09 seated under the pressure existing in cylinder 89 andconsequently oil will escape from cylinder 69 through valve t i.Cylinder 59 will continue on its forward motion until the end of itsstroke, but plunger I 53 will immediately stop. The roller |2| ridesalong the bottom surface of Cam I4I and keeps the valve open during theremainder of the discharge stroke. On the suction stroke ball 09 willimmediately close valve 8| and thereby prevent suction of air intocylinder 69. On the return stroke cylinder 59 will iill with oil in thesame manner described with respect to the operation of the relief valve.

It will be seen therefore that the farther cam IM is'rnovedV to the leftthe shorter will be the stroke of piston 201 and the less liquid thepump will deliver. The stroke of the pump can be adjusted from zero tofull stroke.

Instead of using the check valve and cam mechanism shown and described,control of the stroke of the pump may be attained bysubstitutingtherefor a flow control valve which can be adjusted to bleedoff any desired amount of hydraulic fluid from cylinder 69 during theforward stroke of the cylinder. Thus a longer or shorter piston strokewill be obtained as less or more uid is bled off.

Thus, stationary means is provided for adjustu ing the stroke of thepump or controlling the discharge therefrom: atianyipoint: during thestroke By operating. the' unit as a dual unitl withan pumpfconnected toeach end of the cross-head; two different chemicalsor other liquid canbe pumped by the unit and the delivery. of each chemical can beindependently controlled'so that.-

anyY desired proportion'of the twocan be delivered.

It is claimed:

1. A. variable stroke device comprising. a reciprocable cylinder closedat one end,.aV plunger.

adapted: to reciprocatein said cylinder and ex.-v tending. beyondA theother end of said cylinden.

an inlet and an. outlet valve on saidA cylinder. for; admitting and.discharging liquid, meansA for Lilrewisait is preferred to maintain,

maintaining said outlet valve'in open or closed 30 positionz during anyportion of: the stroke of said. cylinder, and means yfor reciprocatingsaid.cylinderand plunger..

2;. A variable stroke device comprising a. reciprocable cylinder closedat one end, meansfor reciprocating said cylinder, a plunger reciprocablymountedin said cylinder and. extending beyond the other end. thereof,means for admit,-

tingv liquid to and. discharging liquid from said;

cylinder and means for controlling the volume of liquid discharged fromsaid cylinder on. each delivery stroke thereof.

3. A variable stroke dev-ice comprisingj a reciprocable cylinder closedatione end, meansior reciprocating said cylinder, a plunger: ofl smallerdiameter than said cylinder adapted to recipro cate therein and mountedto prevent leakage-ofliquidV from said cylinder, said plunger hav-ingran end extending from the other end of saidthereof parallel tothe lineof` motion ofA said.V

cross-head, a plunger slidably mounted in said cylinder with one endthereof extendingbeyond:

the other end of the cylinder', the internal diameter offsaidcylinder-being substantially greater than the diameter of said plungerexcept ad-v jacent the end from which the plunger'extends, means foradmitting liquid to. and discharging. liquid from said cylinder, meansfor automatically opening said liquid discharge-meansfat. any predetermined point inthe stroke of said cylinden. a crank-arm` mounted. torotate in saidy cross-I head. and to slide therein in a direction per-ypendicular to the direction in which the crosshead reciprocates, a cranktofwhich saidcrank.- arm. is fastened and a` crankshaft` fastenedtosaidcrank.

81 5i A: stroke: adjusting. and; piston actuating' mechanismcomprising across-head, means for reciprocating said. cross-head, a pair of cylin.-v

ders closed-at; one end fastened to oppositesides v of saidcross-head'Withfthe-axes thereof extend-v ing alongflines parallel totherdirection of reciprocation of the cross-head,` means for slidablysupporting. s-aidcylinders, at least one of said cylinders havingmeansfor admitting liquid thereto, andmeans for discharging liquid'therefrom;duringany predetermined portion of' the stroke thereof, and a1 plunger'slidably mounted therein,

one end` ofi which plunger extending outside the,`

other end ofsaidv cylinder.

6; A- stroke. adjusting and, piston actuating mechanism comprising across-head, means for reciprocating saidicrossehead, a pairofslidablysupported cylinders closed at one end fastened to.- oppositesides.- of said cross-head with the.A axes thereof extending alonglinesv parallel with the direction'of reciprocation of said cross-head,aiplunger slidably mounted in each cylinder,l said plungers beingsubstantially smaller inldiameter than the inside diameter of saidcylinder except f at the end of said cylinders, said plungers ex-rtending outside thevother end'of said cylinders, means fork admitting.liquidy to said cylinders, means for automatically discharging liquidfrom said cylindersfdur-ing any portion ofy the stroke thereof and meansfor dischargingliquid from said cylinders when the pressurethereinreaches atpredeterminedr amount..

7'. An adjustable stroke pumping mechanismv comprising a stationarycylinder and a reciprocablecylinder, a. plunger slidably mounted insaidstationary cylinder and a plunger slidably mounted in said reciprocablecylinder said plungersbeing connected to'operate' as a unit, an. inletandan outlet in said stationary cylinder, means to admit liquid to saidreciprocable cylinder during itsv suction stroke, means to automaticallydischarge any predetermined amount of`liquid, from the` reciprocablecylinder during. its forward'stroke andmeans to impart reciproeatingmotion to said reciproeable cylinder.

8; Mechanism in accordance with claim 7 in. which tl'ieplunger. slidablymounted'in the re ciprocabl'ecylinder snugly tsvin the endo the.cylinder'but is ofl smaller diameter than the inside diameter of` thatportion of the cylinder remote from the end from which the plungerprotrudes and said plunger has an enlarged end inside the cylinder toenable the end of the cylinder to positively engage the plunger duringthe' suction stroke.

9'.' An'` adjustable stroke displacement pump comprises a pair ofoppositely disposed stationary cylinders,- a pairV of oppositelydisposedreciprocable cylinders closed. at one end, a, commonI means forimparting reciprocating motion to said reciprocable cylinders, a pistonslidably mounted ineachof said stationary cylinders and a plungerslidably mounted in each of said reciprocable cylinders andi extendingbeyond the other end thereof', each of said reciprocablecylinders beingof smaller internal diameter at its open end than throughout theremainder thereof and each plunger having an enlarged end inside thecylinder adapted to abut' against the narrow end off: the cylinder; thepiston and plunger on each side of: thereciprocatingi means beingconnected" to. move as a` unit, means' on each reciprocable cylinderfor: admitting liquid thereto during the.

sired amount of fluid therefrom during the discharge stroke.

10. A pump in accordance with claim 9 com. prising means forautomatically discharging liquid from said reciprocable cylinders whenthe pressure therein reaches a predetermined amount.

11. A pump in accordance with claim 9 in which the means forautomatically discharging any desired amount of uid from thereciprocable cylinders during the discharge stroke comprises a ballcheck valve mounted on each cylinder, a plunger engaging the ball ineach valve and adapted to unseat the ball and open the valve whenpressurev is applied to the plunger, and a separate movable cam adaptedto engage each plunger at any selected point in the stroke of thecylinder whereby the stroke of each piston can be independentlycontrolled.

12. A stroke adjusting device for a displacement type pump comprising areciprocable cylinder open at one end, an element mounted toyreciprocate in said cylinder, said element extending through the openend of said cylinder, means for admitting liquid to the space betweenthe closed end of said cylinder and said element during the suctionstroke of the pump and means for controlling discharge of liquid fromsaid cylinder at any time during substantially the entire deliverystroke of the pump.

13. A device for controlling the discharge from a displacement type pumpcomprising a reciprocable cylinder open at one end, an element adaptedto reciprocate in said cylinder and extending through the open end ofsaid cylinder, means for admitting liquid to the space between theclosed end of said cylinder and said element during the suction strokeof said pump, means for optionally discharging liquid from said cylinderduring the discharge stroke of the pump, and adjustable stationary meansfor opening said discharging means at any time during operation of thepump and thereby regulate the movement of said pump displacing element.

14. A stroke adjusting device in accordance with claim 12 in which saidmeans for admitting liquid to said cylinder is a ball check valve andsaid means for controlling discharge of liquid from said cylindercomprises a ball check valve, a plunger adapted to be depressed againstand unseat said last mentioned valve, and an adjustable cam for engagingand depressing said plunger at substantially any point in the stroke ofsaid cylinder.

15. A stroke adjusting device for a displacement type pump comprising ahorizontally disposed cylinder, an element extending beyond one end ofsaid cylinder, mounted to reciprocate therein, means for reciprocatingsaid element, means for transferring the reciprocating motion of saidreciprocating means to the displacement element of said pump through aliquid medium, means on the lower side of said cylinder for admittingliquid to said cylinder during the suction stroke of said pump whilepreventing discharge of liquid during the discharge stroke and means atthe top of said cylinder for controlling discharge of liquid therefromat any time during substantially the entire delivery stroke of the pumpwhile preventing intake of liquid or vapor therethrough during thesuction stroke of the pump.

16. A device in accordance with claim 13 in which said adjustablestationary means is adapted to automatically open said discharging meansat any selected point during the discharge stroke of the pump and saiddischarging means is adapted to automatically close at the end of thedischarge stroke of the pump.

17. Mechanism for automatically discharging lluid from a reciprocatingcylinder at any desired point in the stroke thereof comprising a valvemounted on said cylinder adapted to be normally held in closed position,an element one end of which engages said valve in such manner as toenable said valve to be opened upon exerting pressure on the end of saidelement opposite to that which engages the valve, and an elongatedstationary cam adjustable in the directions of reciprocation of saidcylinder adapted to contact and exert pressure on the said opposite endof said element during a predetermined portion of the stroke of saidcylinder.

18. Mechanism in accordance with claim 17 in which the cam is mounted totravel on a stationary, rotatable stem threaded to engage threads onsaid cam.

HARRY J. ANDERSON. MILTON V. HARTMAN.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,238,670 Holbrook Aug. 28, 19171,383,657 Noguera July 5, 1921 1,601,451 Burnett Sept. 28, 19261,650,377 Nixon Nov. 22, 1927 1,785,407 Tourness Dec. 16, 1930 1,867,470Ponthieu July l2, 1932 1,922,264 Shiner Aug. 15, 1933 1,982,770 TollisonDec. 4, 1934 2,006,572 Herrmann July 2, 1935 2,041,468 Grubbs May 19,1936 2,343,962 Dodson Mar. 14, 1944 FOREIGN PATENTS Number Country Date640,983 Germany 1937

